1. Field of the Invention
This invention relates to a tube coupling provided with a locking mechanism by means of lock balls.
2. Description of the Related Art
There have been used various types of safety devices of locking mechanisms in which locking balls are set in an engaging state and a disengaging state selectively by slidably operating sleeves. For example, the assignee of the present application has proposed a tube coupler which is provided at the back of a main sleeve for a locking balls with a sub-sleeve for locking the main sleeve, as disclosed in Jpn. UM Appln. KOKOKU Publication No. 52-29311. With this related art, there occurs no fear that the main sleeve falls off even if an unexpected external force is applied to the main sleeve.
The assignee of the present application has also proposed a tube coupler which is provided at the side of a socket with a sealing mechanism comprising an adjusting ring and an intermediate tubular body slidable in the axial direction of the socket, in order to enhance the sealing effects between the abutting faces of a plug and a socket (see Jpn. UM Appln. KOKOKU Publication No. 58-24069). According to this related art, the sealing mechanism is adjusted externally to increase the sealing effect only by rotating the adjusting ring when the plug and the socket in a connected state.
Although both safety means for the locking mechanism and means for adjusting sealing of abutting ends are useful as the functions of the tube coupler, however, there has not yet been known a tube coupler which has these two means in a single unit.